Recent higher-speed solid-state image pickup apparatuses have caused the proposal of a structure in which a semiconductor compound layer is provided at a transistor.
Japanese Patent Laid-Open No. 2001-111022 discusses a solid-state image pickup apparatus in which a high-melting-metal semiconductor compound layer is not provided on a photodetector of a photoelectric converting section, and a high-melting-metal semiconductor compound layer is provided at a peripheral circuit portion.
Japanese Patent Laid-Open No. 2009-170448 discusses a backside-illumination solid-state image pickup apparatus in which, in order to increase sensitivity of a photoelectric conversion element, a substrate including a pixel portion provided with the photoelectric conversion element and a signal-readout circuit, and a substrate including a peripheral circuit for processing a read-out signal by driving the circuit of the pixel portion are adhered to each other.
In the structure in which a high-melting-metal semiconductor compound layer is provided at the peripheral circuit portion in Japanese Patent Laid-Open No. 2001-111022, since a high-melting metal is provided on the same substrate, the high-melting metal may be diffused to the photoelectric conversion element. Even if a surface of the photoelectric conversion element is protected by an insulating film, the high-melting metal may become diffused in the insulating film since, for example, a step of forming the high-melting metal on the insulating film exists. In addition, for example, a white defect may occur in an image due to leakage current generated as a result of contamination of the photoelectric conversion element by the high-melting metal. Further, in order to form the structure discussed in Japanese Patent Laid-Open No. 2001-111022, it is necessary to determine where to form the high-melting metal semiconductor compound layer on the same substrate, thereby complicating the process.
Accordingly, it is an object of the present invention to provide, by using a simple structure, a solid-state image pickup apparatus in which a high-melting-metal compound layer is disposed at a peripheral circuit portion while a reduction in the characteristics of a photoelectric conversion element, which causes, for example, a white defect to be produced, is suppressed.